Methuen police have closed a city hill to sledding after three sled crashes there, including one so serious that a woman had to be transported by medical helicopter to a Boston hospital.

Over the weekend, a 22-year-old, 17-year-old, and 11-year-old were all injured while sledding on the popular hill at Greycourt Park. The victims suffered head, back, and lower extremity injuries, Methuen Police Lieutenant Michael Pappalardo said. He did not say which victims suffered which injuries.